The trend of having high circuit density leads to problems of thermal dissipation in the PCB (printed circuit board) assembly process. Improved efficiency of thermal dissipation is helpful to make the devices work properly, especially for high power system and its IC packaging.
In some cases, a metal coin is embedded inside the PCB under the high power component or the IC chip, such that heat can be dissipated to the other side of the PCB and can be carried away by another heat sink device or a cabinet physically contacted to the coin.